1. Field of the Invention
The present invention relates to a method for routing with selectable granularity of the rate of asynchronously transmitted message cells, wherein
a counter is established for a block,
the counter works with a clock signal whose cycle is equal to a message cell cycle,
a rate parameter equal to the declared message cell rate corresponds to a counter reading, and
when the counter reading of the counter for the block is reached, a message cells is forwarded.
2. Description of the Prior Art
It is generally standard practice to determine a part of a declared message cell rate with the assistance of a counter employed as divider. In view of the allocation of a declared message rate for a block in the overall message cell rate that is available in a following interface, it is considered obvious to utilize a counter that is clocked in the clock of the message cell rate and that outputs a status character for forwarding a message cell when a counter reading corresponding to the declared message cell rate for the block is reached. It is thereby felt to be disturbing that the step width, which is also referred to as granularity in the technical field, that can be set becomes coarser and coarser with an increase in the declared message cell rate (divisor ratio 1, 2, 3,4 . . . ).
The present invention is thereof directed to improving the known method outlined at the start such that a predetermined step width can be adhered to even given large division relationships of the declared message cell rate in the overall message cell rate.
Therefore, pursuant to the present invention
when forwarding a message cell, the value of a variable Nservfrac is increased by a value that is equal to Tservfrac Modulo 2Z, where
Tservfrac is established by the fractional part of the rate parameter and z is established by 1d=1/percentage granularity; and
when the value range of the variable Nservfrac is outwardly exceeded, one cycle of the clock signal supplied to the counter is suppressed.
Even given a large share of the declared message cell rate for a block in terms of the overall message cell rate, the subject matter of the present invention produces a close matchability of the message cell rate with which the block is actually serviced to the declared message cell rate.
Additional features and advantages of the present invention are described in, and will be apparent from, the Detailed Description of the Preferred Embodiments and the Drawing.